The present invention relates to rotary sprinklers, and particularly to the type of rotary sprinklers widely used for irrigating lawns, gardens, crops, etc.
One known type of rotary sprinkler used for irrigating lawns, gardens, crops, etc., includes a rotatable nozzle carried by a housing and a drive driven by the pressurized water and coupled to the nozzle via a transmission to rotate the nozzle. Such rotary sprinklers, when not used for long periods of time in lawns, open fields, etc., tend to become jammed against rotation by the entry of dirt and other foreign matter into the rotary mechanism, preventing the rotation of the nozzle. When a sprinkler thus becomes jammed, its nozzle discharges the water only to a small portion of the area to be irrigated, thereby leaving the remainder of the area dry. As a result, not only is there a large wastage of water, but also there can be a large loss in the crop yield. Moreover, such sprinklers require frequent maintenance in order to clear the jamming, which results in increased costs and longer down-time of the respective portion of the irrigation system.